import java.util.Scanner;

public class prefix_and {
    public static void main(String[] args) {
        int[] arr = {1, 3, 4, 5, 6, 73, 2, 45, 6, 3};
        int le = arr.length;
        int sum=0;
        int[] prefixand = new int[le];
        Scanner peo = new Scanner(System.in);
        prefixand[0] = arr[0];
        for (int i = 1; i < le; i++) {
            prefixand[i] = prefixand[i-1] +arr[i];
        }
        int left = peo.nextInt() - 1;
        int right = peo.nextInt() - 1;
        sum = prefixand[right] - prefixand[left-1];
        System.out.println(sum);
    }

}
